1. Field of the Invention
The present invention generally relates to image input module adjusting devices and image input module adjusting methods.
2. Description of the Related Art
Recently, image input sensors have been applied to various kinds of electronic apparatuses and used for imaging processes, identification processes and others. In an image input module having such an image input sensor, it is necessary to perform focusing of an image on the image input sensor. For focusing image on the image input, as discussed in Japanese Laid-Open Patent Application Publication No. 2006-64886, the position and the focus of a lens relative to the image input sensor are adjusted.
FIG. 1 shows an example of a related art image input module adjusting device (hereinafter “adjusting device 100”). FIG. 1(A) is a front view of the adjusting device 100, and FIG. 1(B) is a side view of the adjusting device 100.
Referring to FIG. 1, in an image input module 1, an image input sensor 5 is provided in a substantially center position of an upper surface of a board 2. A connector 6 is provided on a lower surface of the board 2. A lens 3 is fixed above the board 2 via a lens mount 4. Image input area adjusting (position adjusting) relative to the image input sensor 5, and focus adjusting of the lens 3 relative to the image input sensor 5 are performed by using the adjusting device 100.
In the adjusting device 100, a fixing base 112 having a device side connector 118 is provided on a base 111. The connector 6 is engaged with the device side connector 118 so that the board 2 is provided in the adjusting device 100. In the following explanation, a mounting position of the board 2 in the design of the adjusting device 100 is called a standard mounting position.
The adjusting device 100 includes an adjusting pattern 117, a lens moving mechanism 120, a motor 122 used for focus adjusting, a hand driving mechanism 124, and other parts for adjusting the image input area relative to the image input sensor 5 and focus adjusting of the lens 3 relative to the image input sensor 5 can be performed using the board 2.
In order to perform the adjusting process of the image input area relative to the image input sensor 5, the connector 6 is connected to the device side connector 118 so that the board 2 is mounted in the adjusting device 100. Thereby positioning of the image input sensor 5 provided above the board 2 and the adjusting pattern 117 provided in the adjusting device 10 is performed.
Next, the lens mount 4 where the lens 3 is connected is mounted on the board 2 and is supported by a hand 125 by driving the hand driving mechanism 124. The hand driving mechanism 124 is attached to a pillar 121 standing on the lens moving mechanism 120. The lens moving mechanism 120 can move on the base 111 in X and Y directions. The hand 125 is moved by the lens moving mechanism 120 via the hand driving mechanism 124 so that the lens 3 is moved above the board 2 in the X and Y directions and thereby the adjusting process of the image input area relative to the image input sensor 5 is performed.
After the adjusting process of the image input area is completed, the focus adjusting process of the lens 3 relative to the image input sensor 5 is performed. This focus adjusting process is performed by using the motor 122. A focus adjusting rotational belt 126 is wound around a lens side pulley 127 connected to the lens 3 and a motor side pulley 128 provided to an output axle of the motor 122.
Under this structure, the motor 122 is rotated so that the lens 3 is rotated via the motor side pulley 128, the rotational belt 126 for focus adjusting, and the lens side pulley 127. While a focus adjusting pattern provided at the adjusting pattern 117 is imaged by the image inputting sensor 5, the position where the lens 3 is focused on the image input sensor 5 is detected.
When this focus adjusting process is completed, the rotational belt 126 for focus adjusting and the lens side pulley 127 are taken out. Then the lens 3 and the lens mount 4 are adhered to each other by adhesive, and the lens mount 4 and the board 2 are adhered to each other. Thus, the adjusting process of the lens 3 relative to the image input sensor 5 is completed.
In the above-discussed adjusting device 100, positioning of the image input sensor 5 and the adjusting pattern 117 is made by engaging the connector 6 provided on the board 2 above which the image input sensor 5 is mounted with the device side connector 118. However, in this way, mounting errors ΔX1, ΔY1, ΔX2, and ΔY2 shown in FIG. 2 and FIG. 3 and engaging gaps ΔX3 and ΔY3 of the connector shown in FIG. 4 are generated.
FIG. 2 shows a mounting error generated when the image input sensor 5 is mounted above the board 2. In FIG. 2, a design sensor position DP1 indicated by a dotted line indicates a standard mounting area in the design of the image input sensor 5.
However, a mounting position where the image input sensor 5 is actually mounted would be a position indicated by a solid line in FIG. 2, that is shifted from the design sensor position DP1. In an example shown in FIG. 2, mounting errors ΔX1 and ΔY1 of the mounting position relative to the design sensor position DP1 are generated. Specific values of the mounting errors in an X direction (X1 and X2 directions) and a Y direction (Y1 and Y2 directions) are ΔX1=±0.1 mm and ΔY1=±0.1 mm, for example.
These mounting errors are generated, as shown in FIG. 3, when the connector 6 is mounted on the board 2. In FIG. 3, a design connector position DP2 indicated by a dotted line is a standard mounting position in the design of the connector 6. However, an actual mounting position of the connector 6 is a position indicated by a solid line in FIG. 3. Accordingly, mounting errors of ΔX2 and ΔY2 of the mounting position relative to the design sensor position DP2 are generated. Specific values of the mounting errors in an X direction and a Y direction are ΔX2=±0.1 mm and ΔY2=±0.1 mm, for example.
In addition, because the connector 6 is inserted in the device side connector 118 when the connector 6 is installed, gaps between the connector 6 and the device side connector 118, namely connector engaging gaps, are generated in an X direction and a Y direction as shown in FIG. 4(A) and FIG. 4(B). Specific values of the connector engaging gaps in an X direction and a Y direction are ΔX3=±0.05 mm and ΔY2=±0.05 mm, for example.
Because of this, when the connector 6 is provided to the device side connector 118, errors ΔXmax and ΔYmax of the board 2 relative to the standard mounting position in the design have values of sums of the mounting errors and the connector engaging gaps, namely ΔXmax=ΔX1+ΔX2+ΔX3=±0.25 mm, and ΔYmax=ΔY1+ΔY2+ΔY3=±0.25 mm.
For example, when a wide angle lens is used, shifts between the adjusting patterns 117 and the center position of the image input sensor 5 at the time of adjusting influence a visual shift after the adjusting. In order to minimize these errors, it is necessary to position the image input sensor 5 with high precision in the adjusting device. However, according to the above-discussed example, because errors of ±0.25 mm exist, sufficient precision of the image input sensor 5 position cannot be achieved.
In addition, the focus adjusting operation is performed by rotating the lens 3 so that engagement position of screw lands formed at a lower part of the lens 3 and screw grooves formed inside the lens mount 4 is changed, and the lens 3 goes up and down. FIG. 5 shows a focus adjusting mechanism where the focus adjusting rotational belt 126 is provided between the lens side pulley 127 and the motor side pulley 128.
However, according to the above-discussed mechanism, in a case where a necessary rotational torque becomes large due to the engagement of the lens 3, the rotational torque may be insufficient so that sliding may occur between the adjusting rotational belt 126 and each of the lens side pulley 127 and the motor side pulley 128. This is an obstacle to proper focus adjusting. In addition, in a case where a large torque is applied to the lens mount 4 for focus adjusting, a space or gap between the lens mount 4 and the board 2 may be generated. Light may enter into the lens 3 via this space so that an image may be deformed.